An integrated series of structural and functional studies of the frog retinal rod photoreceptor membranes are proposed. X-ray scattering experiments are planned to establish the absolute concentration of water and solids per lamellar repeat. Absolute electron densities will also be derived by varying electron density of aqueous compartments of the rod, using glycerol-Ringer solutions. Thus we plan to obtain absolute electron density profiles of unbleached and bleached disk membranes to 10A resolution. The concentrations of water and solids in the rod will be experimentally correlated with the refractive index of the rod. The birefringence gradient of the rod will be investigated to establish its potential form component. The gradient of form birefringence will indicate limits of the systematic substitution disorder of the outer segment. Rod outer segment lipids will also be examined using x-ray and freeze-fracture techniques. Electron density profiles of rod lipids and rod-lipid-rhodopsin recombinant membranes will be put on an absolute scale. Structural effects of Vitamins A and E, and controlled lipid-peroxidation will also be studied. Attempts to increase the domain size of the 2-dimensional crystal lattices observed in the disk membrane will involve isolated rod outer segments, isolated disk membranes and lipid-rhodopsin recombinants. We will test the effects of pH, ionic strength, ionic composition, degree of dehydration, lipid composition and temperature on the extent of lattice formation. Induction of lattices will be followed by x-ray scattering, freeze-fracture and negative staining techniques. The variation of membrane fracture face textures will be examined as a function of position along the rod axis, as will be the distribution of paracrystalline inclusions. Correlated low-temperature x-ray scattering and freeze-fracture studies will further assess the relationship between native and frozen membrane structure. Low angle x-ray solution scattering studies of rhodopsin-detergent micelles will explore the shape of rhodopsin and opsin in both regenerable and non-regenerable detergents. Bleaching and catron-dependent densities within the terminal loops will be examined. Preceding structural studies will be correlated with electrophysiological studies of disk membranes and lipid-rhodopsin recombinant vesicles fused to solvent-free bimolecular lipid membranes.